This invention is generally directed to novel anilide couplers, and processes for the preparation thereof. More specifically, the present invention is directed to anilide couplers which can be selected for the preparation of photogenerating pigments, especially photogenerating azo pigments which are sensitive to red and near infrared wavelengths, when these pigments are incorporated into imaging members such as xerographic imaging members comprised of a supporting substrate, the aforementioned photogenerating azo pigments, and a charge transport layer. In one embodiment, thus the present invention is directed to anilide coupler obtained from 2,8-dihydroxy-3-naphthoic acid, reference U.S. Pat. No. 5,130,443, the disclosure of which is totally incorporated herein by reference, for obtaining photogenerating azo pigments wherein these pigments absorb light beyond 400 to 650 nanometers of traditional azo pigments of the prior art, and more specifically, wherein the azo pigments prepared from the anilide couplers of the present invention absorb in the wavelength region of from 650 to 850 nanometers. Thus, in embodiments the present invention is directed to novel couplers and processes thereof, which couplers can be utilized to prepare photogenerating pigments in an economical manner. Also, with the present invention there can be prepared bisazo, trisazo and similar photogenerating pigments from the couplers illustrated herein.
The anilide couplers can be prepared from 2,8-dihydroxy-3-naphthoic acid. In one embodiment, the process comprises the reaction of 2,8-dihydroxy-3-naphthoic acid, an aromatic hydroxy compound, such as phenol, and a catalyst like phosphorous oxychloride, separating the resulting 2,8-dihydroxy-3-naphthoate, thereafter reacting the naphthoate with aniline in the presence of a solvent like N-methyl pyrrolidinone, and isolating the product 2,8-dihydroxy-3-naphthanilide. The resulting anilide can then be reacted as illustrated herein to provide azo, bisazo, trisazo, and the like photogenerating pigments which are sensitive to red and infrared light enabling their use in imaging members selected for electrophotographic imaging and printing systems, especially wherein light emitting diodes and diode lasers are utilized. More specifically, the couplers resulting with the processes of the present invention can be selected for the preparation of azo photogenerating pigments, reference for example U.S. Pat. Nos. 4,916,039 and 4,925,758, the disclosures of which are totally incorporated herein by reference. The aforementioned photogenerating pigments can be selected for layered photoresponsive imaging members comprised of a charge transport layer, a photogenerating layer and a supporting substrate. More specifically, the photogenerating pigments that can be obtained with the processes of the present invention can be selected for layered photoconductive imaging members with improved xerographic properties, inclusive of high charge acceptance, low dark decay, high photosensitivity, including photosensitivity in the wavelength regions of from about 650 to about 850 nanometers, enabling their selection for electrophotographic, especially xerographic imaging systems, LED printers, and diode laser printers. The imaging members can be comprised of photoconductive layers comprised of the photogenerating pigments and thereover charge or hole transport layers, especially those comprised of aryl amines, which members can be sensitive to light in the wavelength region of from about 750 to about 850 nanometers. The resulting members are responsive to red and near infrared illumination originating from laser printing apparatuses wherein, for example, gallium arsenide diode lasers are selected. The photoresponsive imaging members can also, for example, contain, situated between a photogenerating layer and a hole transporting layer, or situated between a photogenerating layer and a supporting substrate with a charge transport layer in contact with the photogenerating layer, a photoconductive composition comprised of the photogenerating azo pigments.
Examples of advantages associated with the processes of the present invention include the provision of couplers that enable infrared sensitive photogenerating pigments; obtaining couplers with high purity, for example from about 95 to about 99 percent or higher in embodiments; immediate utilization of the couplers obtained for the preparation of bisazo photogenerating pigments; scale up to manufacturing conditions is enabled in embodiments thereof; the products obtained can be, after synthesis, selected for the preparation of photogenerating azo pigments, and wherein the resulting xerographic properties of the photoconductive members such as dark decay, charge acceptance, and charge stability are acceptable; and the like. Two important advantages associated with the present invention are that the photogenerating pigments obtained absorb at longer wavelengths as compared to, for example, azo pigments obtained from couplers without the 8-position hydroxy; and that the processes are very econimical especially as compared to obtaining photogenerating pigments from the anilide couplers of 2-hydroxy-11H-benzo(a)carbazole-3-carboxylic acid.
The preparation by certain method of anilide couplers is known. More specifically, there is disclosed in Japanese Laid Open 59-137459, 1984, the preparation of 2-hydroxy-11H-benzo(a)carbazole-3-carbohydrozide by initially preparing a methyl ester (methyl 2-hydroxy-11H-benzo(a)carbazole-3-carboxylate) and condensing this ester with a hydrazine. Also, in the Color Index, Third Edition, Volume 4, published by the Society of Dyes and Colorants, there is illustrated the preparation of methoxy anilides, such as 2-hydroxy-11H-benzo(a)carbazole-3-carbox-2'-methyl-4'-methoxyanilide, by the condensation of an acid with an appropriate aniline. Other representative prior art disclosing the preparation of couplers include U.S. Pat. Nos. 4,916,039 and 4,925,758 wherein there is illustrated the conversion of an appropriate acid to an acid halide such as acid chloride, and subsequently reacting the resulting acid halide with an aniline to obtain an anilide coupler.
In a patentability search report there were located U.S. Pat. Nos. 4,418,133; 4,480,019; 4,571,369 and 4,713,307.
Also, many processes are known for the preparation of azo photogenerating pigments, such as azotization and coupling, reference U.S. Pat. No. 3,898,084. Examples of aromatic amines selected for the preparation of azo pigments include 2,7-diaminofluorenone, reference for example, U.S. Pat Nos. 4,797,337; 4,830,924; 4,822,705; 4,596,754; 4,618,672; 4,481,271; 4,400,455; 4,390,608; 4,327,176; 4,314,015; 4,299,015; 4,299,896 and 4,551,404 possess in many instances high sensitivity and high electrical stability. Azo pigments synthesized from anilide couplers of 2-hydroxy-11H-benzo(a)carbazole-3-carboxylic acid enable imaging members with photoresponses at longer wavelengths, for example beyond 650 nanometers.
In U.S. Pat. No. 4,916,039 there are disclosed photoconductors with charge generating pigments comprised of certain azo compounds, reference the formula illustrated in the Abstract of the Disclosure, and in column 3. The aforementioned azo pigments are prepared by the coupling reaction of 2-hydroxy-3-carbamoylbenzo-alpha-carbazole derivatives of Formula VI with diazonium salts, reference columns 6 and 7. The coupling reaction is accomplished by dissolving the diazonium salts and a coupler, such as those obtained with the processes of the present invention, in an organic solvent, such as DMF and DMSO, and adding dropwise thereto an alkaline aqueous solution at a temperature of from about -10 to about 40.degree. C., see column 7 for example. A similar teaching is present in U.S. Pat. No. 4,925,758.
Imaging members with certain bisazo pigments are known, reference for example U.S. Pat. No. 3,898,084, which discloses, for example, the azo pigment chlorodiane blue in a photoconductive imaging member. The aforementioned chlorodiane blue can be prepared by azotizing dichlorobenzidine in HCl, for example 18 percent of HCl, by the addition of a sodium nitrite, followed by the addition of HBF.sub.4, enabling the formation of the tetrazonium salt. This salt can then be coupled with 2-hydroxy-3-naphthanilide to permit the formation of the chlorodiane blue pigment, which formation is accomplished in the presence of sodium acetate.
U.S. Pat. No. 3,574,181 discloses disazo compounds useful as coloring agents. Composite electrophotographic photosensitive materials containing various azo compounds are disclosed in U.S. Pat. No. 4,618,672, wherein bisazo compounds particularly suitable for use in the charge generating layer of a layered electrophotographic photoconductor are illustrated. Similarly, an article by M. Hashimoto entitled "Electrophotographic Sensitivity of Fluorenone Bisazo Pigments", Electrophotography, Vol. 25, No. 3 (1986), discloses disazo compounds as charge generating materials in electrophotographic layered photoreceptors. Further, Japanese Patent Kokai No. 54-20736 discloses disazo pigments as constituents in electrophotographic processes. Japanese Patent 58-177955 also discloses many disazo compounds suitable for use in the photosensitive layer of an electrophotographic device.
U.S. Pat. No. 4,713,307, the disclosure of which is hereby totally incorporated by reference, discloses photoconductive imaging members containing a supporting substrate, certain azo pigments as photogenerating materials, and a hole transport layer that preferably contains an aryl diamine compound dispersed in an inactive resinous binder. The aforementioned azo pigments can be obtained from the couplers generated with the processes of the present invention.
U.S. Pat. No. 4,797,337, the disclosure of which is totally incorporated herein by reference, discloses a photoconductive imaging member comprising a supporting substrate, a hole transport layer, and a photogenerating layer comprising specific disazo compounds, which disazo compounds are prepared as illustrated herein, that is by the azotization and coupling reactions illustrated in the aforementioned prior art.
Additional references illustrating layered organic electrophotographic photoconductor elements with azo, bisazo, related compounds, and processes thereof include U.S. Pat. Nos. 4,390,611, 4,551,404, and 4,596,754, Japanese Patent 60-64354, U.S. Pat. Nos. 4,400,455, 4,390,608, 4,327,168, 4,299,896, 4,314,015, 4,486,522, 4,486,519, 4,555,667, 4,440,845, 4,486,800, 4,309,611, 4,418,133, 4,293,628, 4,427,753, 4,495,264, 4,359,513, 3,898,084, 4,830,944, and, 4,820,602, and Japanese Patent Publication 60-111247.
In U.S. Pat. No. 4,833,052, the disclosure of which is totally incorporated herein by reference, there are illustrated certain bisazo photoconductive imaging members. Examples of bisazo compounds disclosed in this patent include those of the formulas as illustrated in column 4, such as 4,4'-bis(1"-azo-2"-hydroxy-3"-naphthanilide)-1,1'-dianthraquinonylamine.
The following United States patents are also mentioned: U.S. Pat. No. 4,830,943 relating to a photoconductor with a disazo having couplers, such as anilides, carbazole, and the like; U.S. Pat. No. 4,833,052 which discloses a photoconductive imaging member comprising a disazo compound with an azoic coupler, such as an anilide and the like, note column 7, lines 44 to 58; U.S. Pat. No. 4,868,880 which discloses a photosensitive layer comprising an azo pigment having an organic residue, see column 2, lines 53 to 65; and U.S. Pat. No. 4,830,944 which discloses a charge generation material comprising a disazo pigment with couplers, such as those derived from carboxylic acids.